Transmission and reflection of phonons and rotons at the superfluid helium-solid interface

Abstract

HeII quasiparticles with the interface: their transmission, reflection and conversion into each other. These are the fundamental elementary processes that determine the heat exchange between HeII and a solid, and the associated phenomena, such as the Kapitza temperature jump (see for example [11]). We investigate all these phenomena. The probability of creation of each quasiparticle at the interface is derived for all cases. The failures of attempts to detect R − rotons prior to experiments [3] is explained, and predictions are made for new experiments on the interaction of phonons and rotons with a solid and the creation of R − rotons at the interface by high energy phonons (h-phonons). arXiv:1206.3678v1 [cond-mat.other]

Kapitza resistance between superfluid helium and solid: Role of the boundary

“…These puzzling features suggest that transmission mechanisms due to surface boundary non ideality (surface roughness, impurities, dislocations, surface orientation, change in He density close to the surface, defects …) have to play an important role. And microscopic descriptions of scattering at the boundary are therefore necessary [5][6][7][8].…”

Spin-wave wells revisited: From wavelength conversion and Möbius modes to magnon valleytronics

“…Very different behavior is expected for waves whose dispersion relation has frequency minima at finite (nonzero) wave vectors. Such a dispersion relation is found, e.g., for rotons in liquid helium [3][4][5][6], for electrons in graphene near the Fermi level [7][8][9][10], and for dipole-exchange spin waves-wavelike excitations of the magnetization in magnetically ordered materials [11][12][13]-in the backward-volume dipole-exchange spin-wave (BVDESW) geometry [12,14]. The propagation, backscattering, and confinement of this latter type of spin wave is studied theoretically in this paper.…”

A new ripplon branch in He II

“…and in more detail in [15]. This model was used in [16], [17] and [15] to describe interaction of He II phonons and rotons with solid interfaces.…”

“…and in more detail in [15]. This model was used in [16], [17] and [15] to describe interaction of He II phonons and rotons with solid interfaces. It is based on the fact, that in a quantum fluid the atoms are delocalized, as their thermal de Broglie wavelength is greater than the atom spacing.…”

“…The equations of ideal liquid, which follow from them, do not form a closed system, and are supplemented by the equation of state, which specifies the functional relation between pressure and density. As shown in [14,15], the equation of state for small deviations of the system from equilibrium in the general case is non-local, with some difference kernel h(r). The ripplons' dispersion equation is obtained in algebraic form, and its analytic solutions are derived in limiting cases.…”